A network node, such as a network control node like a CSCF or an application server, executing forking forwards only the first successful response message arriving from a forking branch, which enables the charging function in the forking node and in nodes in the backward direction from this point to apply charges only for the ''winning'' branch. By including a special Reason header sent in a BYE request of ''unused'' successfully contacted branches, charging function in nodes in the forward direction from the forking point are allowed to suppress charges for such unused branches. This is applicable both for online and offline charging methods as defined, for example, by 3GPP.